More and more vehicle electronic devices such as vehicle GPS terminals, vehicle electric dogs, automobile reversing radars, driving recorders, and vehicle navigating systems, etc. are developed, which bring various conveniences to vehicle owners. However, currently these types of vehicle electronic devices are generally not equipped with independent power supplying system, and most of them use vehicle battery as their power source. The increase of electronic devices carried on the vehicles will place increasing pressure on power supply of internal batteries of the vehicles.
Battery is also known as storage battery. A storage battery is a type of battery that converts chemical energy into electrical energy. A battery usually used in vehicles is a lead-acid storage battery, i.e., a storage battery mainly made of lead and its oxide and with sulfuric acid solution as its electrolyte. The battery generally has the following functions in a vehicle:    1. As a power source for supplying a starting system, ignition system, electronic fuel injection system and other electrical devices of the vehicle, the battery is required to release a starting current as high as 200 A when the engine starts.    2. When the engine stops or operates at a low speed, the battery supplies power to various electronic devices of the vehicle.    3. When the power requirement of the vehicle exceeds the power supply capability of an electric generator, the battery provides auxiliary electricity.    4. The battery also functions as a voltage stabilizer for the power supply system of the whole vehicle, mitigating an impulse voltage of the power supply system to protect various electronic devices on the vehicle.    5. During the normal operation of the engine, extra electricity generated by the electric generator that hasn't been consumed by the vehicle can be stored by means of charging the battery with said extra electricity.
The first function mentioned above involves high current discharging, while the second to the fifth functions involves low current discharging. Given same time period, the high current discharging causes more damages to a battery than the low current discharging. The main reason is that the super saturation degree of lead sulfate formed at the solid-liquid interface is too high such that a relatively larger amount of lead sulfate crystal is formed and deposits at the solid-liquid interface, which not only blocks the micro-holes of the battery plates but also blocks the micro-holes of the separation plate. Thus, branch crystals are more likely to be generated. Moreover, many micro crystals may drop off during charging or discharging period of the battery, which will cause damages to the battery. Furthermore, due to the low diffusion speed of sulphuric acid, sulphuric acid can only reach the shallow layer of the electrolyte such that more alpha lead dioxide are discharged and converted, which may soften the pole panels easily and significantly reduce the lifetime of the battery.
The average lifetime of a vehicle battery is about 2 years. The number of vehicle in China has exceeded 100 millions in 2011. Calculated according to the average lifetime and the number of vehicles, about 50 millions batteries need to be replaced each year, which not only increases the use cost of vehicles but also is adverse to environment protection, as the replaced vehicle batteries will be discarded.
Chinese patent publication No. CN1801524A discloses an online maintainer for large capacity sealed lead acid storage battery. The maintainer has a DC power source, a starting signal circuit, a single-chip processor circuit, a shaping driver circuit, and an electronic switch. The DC power source supplies a desired DC current to the electronic switch, and the electronic switch converts the DC current into a pulse current and supplies the converted pulse current to a battery being repaired. After receiving a pulse instruction from the starting signal circuit, the single-chip processor circuit outputs a waveform with variable pulse width according to voltage detection and temperature detection data of the battery being repaired. The shaping driver circuit is used to control the on/off state of the electronic switch and the amplitude of a repair pulse current. Although in this patent application, pulsing technology is used to eliminate or reduce the crystallization of lead sulfate within the lead acid storage battery so as to recover the energy storage capacity, it still cannot protect the storage battery. Instead, it only repairs the battery with limited effect at the cost of consuming the electricity.